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Classification and mode of action of disinfectants PHARMACEUTICAL MICROBIOLOGY (BP303T) Unit-III Part-3

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Classification and mode of action of disinfectants PHARMACEUTICAL MICROBIOLOGY (BP303T) Unit-III Part-3

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PHARMACEUTICAL MICROBIOLOGY (BP303T)Unit-III Classification and mode of action of disinfectants. DISINFECTANT
Definition: Ideal properties of disinfectants: CLASSIFICATION OF DISINFECTANTS: Based on consistency 1. Liquid (E.g., Alcohols, Phenols) 2.Gaseous (Formaldehyde vapor, Ethylene oxide). Based on spectrum of activity 1. High level disinfectant
2. Intermediate level disinfectant
3. Low level disinfectant .Based on mechanism of action: 1.Action on membrane2.Denaturation of cellular proteins 3.Damage to nucleic acids 4.Oxidation of essential sulfhydryl groups of enzymes 5.Alkylation of amino-, carboxyl- and hydroxyl group. MODE OF ACTION AND APPICATION OF DISINFECTANT
Acid and alkalies
Halogens
Heavy metals
Phenols and its derivatives
Alcohol
Aldehydes
Dyes:
Quaternary ammonium compounds
Detergents and soaps.

PHARMACEUTICAL MICROBIOLOGY (BP303T)Unit-III Classification and mode of action of disinfectants. DISINFECTANT
Definition: Ideal properties of disinfectants: CLASSIFICATION OF DISINFECTANTS: Based on consistency 1. Liquid (E.g., Alcohols, Phenols) 2.Gaseous (Formaldehyde vapor, Ethylene oxide). Based on spectrum of activity 1. High level disinfectant
2. Intermediate level disinfectant
3. Low level disinfectant .Based on mechanism of action: 1.Action on membrane2.Denaturation of cellular proteins 3.Damage to nucleic acids 4.Oxidation of essential sulfhydryl groups of enzymes 5.Alkylation of amino-, carboxyl- and hydroxyl group. MODE OF ACTION AND APPICATION OF DISINFECTANT
Acid and alkalies
Halogens
Heavy metals
Phenols and its derivatives
Alcohol
Aldehydes
Dyes:
Quaternary ammonium compounds
Detergents and soaps.

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Classification and mode of action of disinfectants PHARMACEUTICAL MICROBIOLOGY (BP303T) Unit-III Part-3

  1. 1. PHARMACEUTICAL MICROBIOLOGY (BP303T) Unit-IiI Part-4 Classification and mode of action of disinfectants. Name: Ms. Pooja Deepak Bhandare Assistant Professor G H RAISONI UNIVERSITY SCHOOL OF PHARMACY
  2. 2. DISINFECTANT Definition: • Disinfection is the process of destruction or removal of microorganisms and reducing them to a level not harmful to health. • Disinfectants generally kills the sensitive vegetative cells but not the heat resistant endospores. • Disinfection is less effective than Sterilization process • Usually disinfectants are bacteriocidal. Occasionally it maybe bacteriostatic.
  3. 3. Ideal properties of disinfectants: • Broad spectrum • Non toxic • Fast acting • Odourless • Surface compatibility • Economical
  4. 4. • Easy to use • Solubility and miscibility • Not affected by physical factors • Stable on storage • Several terms used to describe the physical processes and chemical agents employed in controlling microorganisms are as below.
  5. 5. CLASSIFICATION OF DISINFECTANTS Disinfectants are classified on the basis of their consistency, spectrum of activity and mechanism of action: • Based on consistency : On the basis of their consistency state of matter, disinfectant are classified two types a. Liquid (E.g., Alcohols, Phenols) b. Gaseous (Formaldehyde vapor, Ethylene oxide)
  6. 6. • Based on spectrum of activity a. High level disinfectant : These disinfectant are used against certain types of endoscopes and surgical instruments with plastic components e.g. glutaraldehyde (2%), hydrogen peroxide (6%), acetic acid (0.2%), chlorine compounds etc. b. Intermediate level disinfectant : These disinfectant may not be effective against bacterial spores. These disinfectant are used for disinfection of laryngoscope and fiberoptic endoscopes e.g. alcohol, iodophores, phenolic compound etc. c. Low level disinfectant : These disinfectant are used against items which come in contact with the patient, such as stethoscopes, electrocardiogram electrodes, etc. e.g quaternary ammonium compounds, phenols, hydrogen peroxide solution, alcohol, etc.
  7. 7. • Based on mechanism of action a. Action on membrane: These disinfectant act on plasma membrane of microorganisms and destroy it. They mainly active in combination of water E.g., Alcohol (ethanol , isopropanol), detergent b. Denaturation of cellular proteins: These components mainly denature of protein and enzymes of the cell wall (E.g., Alcohol, Phenol) c. Damage to nucleic acids : Disinfectant having alkylating action mainly act on proteins and damage of nucleic acid (E.g., Ethylene Oxide, Formaldehyde)
  8. 8. d. Oxidation of essential sulfhydryl groups of enzymes : These components mainly produce destructive hydroxyl free radicals that attack membrane lipid, DNA and other cell components. (E.g., H2O2, Halogens) e. Alkylation of amino-, carboxyl- and hydroxyl group: These components mainly responsible for alkylating the amino, carboxyl, hydroxyl, and sulfhydryl groups in the enzyme and protein molecules (E.g., Ethylene Oxide, Formaldehyde)
  9. 9.  MODE OF ACTION AND APPICATION OF DISINFECTANT: • Chemical agents are most commonly used as disinfectants. These chemical agents are classified as follows: 1. Acid and alkalies 2. Halogens 3. Heavy metals 4. Phenols and its derivatives 5. Alcohol 6. Aldehydes 7. Dyes: 8. Quaternary ammonium compounds 9. Detergents and soaps.
  10. 10. 1. Acid • Examples: acetic acid, citric acid Acidic disinfectants function by destroying the bonds of nucleic acids and precipitating proteins. Acids also change the pH of the environment making it detrimental to many microorganisms. Concentrated solutions of acids can be caustic, cause chemical burns, and can be toxic at high concentrations in the air. These characteristics limit their use. The antimicrobial activity of acids is highly pH dependant. Acids have a defined but limited use as disinfectants.
  11. 11. • Acetic acid is usually sold as glacial acetic acid (95% acetic acid) which is then diluted with water to make a working solution concentration of 5%. The concentrated form is corrosive to the skin and lungs, but the typical dilution (5%) is considered non-toxic and non-irritating. Acetic acid is typically applied by spraying, misting or immersing an item in a diluted solution. Household vinegar is a 4-5% solution of acetic acid (by volume). Acetic acid has poor activity in organic material
  12. 12. 2. Alkalis • Examples: sodium or ammonium hydroxide, sodium carbonate, calcium oxide Alkaline agents work by saponifying lipids within the envelopes of microorganisms. The activity of alkali compounds is slow but can be increased by raising the temperature. Alkalis have good microbicide properties, but are very corrosive agents and personal protection precautions should be observed. • Sodium hydroxide (lye, caustic soda, soda ash) is a strong alkali used to disinfect buildings but is highly caustic. Protective clothing, rubber gloves, and safety glasses should be worn when mixing and applying the chemical. Lye should always be carefully added to water. Never pour water into lye; a very violent reaction will occur as well as the production of high heat that can melt plastic containers. Sodium hydroxide is corrosive for metals. It is considered an effective FMD disinfectant.
  13. 13. • Ammonium hydroxide is an effective disinfectant against coccidial oocysts however strong solutions emit intense and pungent fumes. This substance is not considered effective against most bacteria. General disinfection should follow the use of this compound. • Sodium carbonate (soda ash, washing soda) has been used in a hot solution (180o F) for disinfecting buildings, which have housed animals with FMD. It is more effective as a cleanser than a disinfectant since it lacks efficacy against some bacteria and most viruses. A 4% solution has been listed as an approved chemical for the FMD virus. It has poor activity in the presence of organic material and can be deactivated by hard water. It can be irritating and requires protective clothing and is harmful to aquatic life. • Calcium oxide (quicklime) becomes lime wash when mixed with water. This has biocidal effects on some bacteria and virus and is sometimes spread on the ground following depopulation of infected premises and has also been used to retard putrefaction of buried carcasses after depopulation. It is not very effective against the FMD virus.
  14. 14. 2. HALOGENS: • Mode of action: Oxidizing agents and cause damage by oxidation of essential sulfydryl groups of enzymes. Chlorine reacts with water to form hypochlorous acid, microbicidal. • Examples: Chlorine compounds (chlorine, bleach, hypochlorite) and iodine compounds (tincture iodine, iodophores) • Application: i. Effective disinfectants and antiseptics ii. Microbicidal iii. Also sporicidal with longer exposure
  15. 15. 3. HEAVY METALS: • Mode of action: Act by precipitation of proteins and oxidation of sulfydryl groups They are bacteriostatic • Examples: Mercuric chloride, silver nitrate, copper sulfate, organic mercury salts (e.g., mercurochrome, merthiolate) • Applications: Silver compounds as antiseptics Silver sulfadiazine for burns Silver nitrate in eye infection Merthiolate in 1:10000 -preservation of serum Copper salts as a fungicide
  16. 16. 4.PHENOL: • Mode of action: Act by disruption of membranes, precipitation of proteins and inactivation of enzymes • Examples: 5% phenol, 1-5% Cresol, 5% Lysol, hexachlorophene, chlorhexidine, chloroxylenol • Applications: i. As disinfectants at high concentration and as antiseptics at low concentrations ii. Bactericidal, fungicidal, but are inactive against spores and most viruses iii.Effective in the presence of organic material and remain active on surfaces long after application
  17. 17. 5. ALCOHOLS: Mode of action: Alcohols dehydrate cells, disrupt membranes and cause coagulation of protein • Examples: Ethyl alcohol, isopropyl alcohol and methyl alcohol • Application: i. 70% ethyl alcohol (spirit) is used as antiseptic on skin ii. Isopropyl alcohol is preferred to ethanol • iii. Also used to disinfect surfaces • Used to disinfect clinical thermometers • iv. Methyl alcohol kills fungal spores, hence is useful in disinfecting inoculation hoods • Disadvantages: Skin irritant, volatile (evaporates rapidly), inflammable
  18. 18. 6.ALDEHYDES: • Mode of action: Acts through alkylation of amino-, carboxyl- or hydroxyl group, damages nucleic acids. It kills all microorganisms, including spores • Examples: Formaldehyde, Glutaraldehyde • Application: i. Bactericidal, sporicidal, and also effective against viruses • ii. Can also be used as chemical sterilants 40% Formaldehyde (formalin): for surface disinfection and fumigation iii. 10% formalin with 0.5% tetraborate sterilizes clean metal instruments 2% glutaraldehyde • iv. To disinfect hospital and laboratory equipments • v. An exposure of at least 3 hours at alkaline pH is required for action by glutaraldehyde • vi. Especially effective against tubercle bacilli, fungi, and viruses
  19. 19. 7. Quaternary ammonium compound: • Mode of actions: Disruption of cell wall and membrane. They also inactive enzyme and denature protein. • Examples: • Cationic detergents are known as quaternary ammonium compounds (or quat) • • Cetrimide and benzalkonium chloride act as cationic detergents • Application: • active against vegetative cells, Mycobacteria and enveloped viruses • As disinfectants at dilution of 1-2% for domestic use and in hospitals. • Used for control of microorganisms on floors, walls, nursing home and other public place
  20. 20. 8. DYES: • Acridine dyes, Aniline dyes • Act by interfering with the synthesis of nucleic acids and proteins in bacterial cells • Acridine dyes such as acriflavin and aminacrine • More effective against gram positive bacteria than gram negative bacteria and are more bacteriostatic in action • •Aniline dyes (such as gentian violent, crystal violet, and malachite green) • •Also more active against Gram-positive bacteria than against Gramnegative organisms • Applications: i. Topically as antiseptics, on skin treat bacterial skin infections ii. The dyes are used as selective agents in certain selective media
  21. 21. THANK YOU

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